In industrial measurements technology, especially also in connection with the control and monitoring of automated manufacturing processes, for ascertaining characteristic measured variables of media, for example, liquids and/or gases, flowing in a process line, for example, a pipeline, often measuring systems are used, which, by means of a measuring transducer of vibration type and, connected thereto, a driving, and evaluating, electronics (most often accommodated in a separate electronics housing) induce reaction forces, for example, Coriolis forces, in the flowing medium and produce, derived from these, a measurement signal correspondingly representing the at least one measured variable, for example, mass flow, density, viscosity or some other process parameter.
Measuring systems of this kind, which are often formed by means of an inline measuring device in compact construction with integrated measuring transducer, such as, for instance, a Coriolis mass flow meter, have been known for a long time and have proven themselves in industrial use. Examples of such measuring systems having a measuring transducer of vibration type, or also individual components of thereof, are described e.g. in EP-A 317 340, JP-A 8-136311, JP-A 9-015015, US-A 2007/0119264, US-A 2007/0119265, US-A 2007/0151370, US-A 2007/0151371, US-A 2007/0186685, US-A 2008/0034893, US-A 2008/0141789, U.S. Pat. Nos. 4,738,144, 4,777,833, 4,777,833, 4,801,897, 4,823,614, 4,879,911, 5,009,109, 5,024,104, 5,050,439, 5,291,792, 5,398,554, 5,476,013, 5,531,126, 5,602,345, 5,691,485, 5,796,010, 5,796,011, 5,796,012, 5,804,741, 5,869,770, 5,945,609, 5,979,246, 6,047,457, 6,092,429, 6,073,495, 6,311,136, 6,223,605, 6,330,832, 6,397,685, 6,557,422, 6,651,513, 6,666,098, 6,691,583, 6,840,109, 6,883,387, 7,017,424, 7,040,179, 7,073,396, 7,077,014, 7,080,564, 7,216,550, 7,299,699, 7,360,451, 7,392,709, WO-A 00 14 485, WO-A 01 02 816, WO-A 08/013545, WO-A 08/07 7574 or WO-A 99 40 394. Each of the therein illustrated, measuring transducers comprises at least one, essentially straight, or at least one, curved, measuring tube for conveying the medium, which can, in given cases, also be extremely cold or extremely hot.
During operation of the measuring system, the at least one measuring tube is caused to vibrate for the purpose of generating forms of oscillation influenced by the medium flowing through the tube.
For exciting oscillations of the at least one measuring tube, measuring transducers of vibration-type include an exciter mechanism driven during operation by an electrical driver signal, e.g. a controlled electrical current, generated and correspondingly conditioned by the mentioned driver electronics. The exciter mechanism excites the measuring tube, by means of at least one electromechanical oscillation exciter, especially an electrodynamic, oscillation exciter, through which electrical current flows during operation and which acts essentially directly to the measuring tube, to execute bending oscillations in the wanted mode. Furthermore, such measuring transducers include a sensor arrangement with oscillation sensors, especially electrodynamic oscillation sensors, for at least pointwise registering of inlet-side and outlet-side oscillations of the at least one measuring tube, especially those of the Coriolis mode, and for producing electrical sensor signals influenced by the process parameters to be registered, such as, for instance, the mass flow or the density. As, for example, described in U.S. Pat. No. 7,216,550, in the case of measuring transducers of the type being discussed, in given cases, also the oscillation exciter can, at least at times, be used as oscillation sensor and/or an oscillation sensor can, at least at times, be used as oscillation exciter.
As excited oscillation form—the so-called wanted mode—in the case of measuring transducers with a curved, e.g. U, V, or Ω shaped measuring tube, normally that eigenoscillation form is selected, in which the measuring tube moves in a pendulum-like manner, at least partially at a lowest natural resonance frequency, about a longitudinal axis of the measuring transducer, in the manner of a cantilever fixed at one end, as a result of which mass flow dependent, Coriolis forces are induced in the medium flowing through the measuring tube. These in turn lead to the fact that, superimposed on the excited oscillations of the wanted mode, in the case of curved measuring tubes, thus pendulum-like cantilever oscillations, are bending oscillations of the same frequency corresponding to at least one, also natural, second oscillation form, the so-called Coriolis mode. In the case of measuring transducers with curved measuring tubes, these cantilever oscillations, caused by Coriolis forces, correspond usually with that eigenoscillation form in which the measuring tube also executes rotational oscillations about a vertical axis oriented perpendicularly to the longitudinal axis. In the case of measuring transducers with straight measuring tubes, for the purpose of generating mass flow dependent, Coriolis forces, often a wanted mode is selected in which the measuring tube at least partially executes bending oscillations essentially in a single plane of oscillation, such that the oscillations in the Coriolis mode are formed, accordingly, as bending oscillations coplanar with the oscillations of the wanted mode, and are of the same oscillation frequency.
As a result, of the superimposing of wanted mode and Coriolis mode, the oscillations of the vibrating measuring tube registered by the sensor arrangement at the inlet and outlet sides of the measuring tube have a mass flow dependent, measurable, phase difference. Normally, the measuring tubes of such measuring transducers, e.g. those used in Coriolis mass flow meters, are excited during operation at an instantaneous, natural resonance frequency of the oscillation form selected for the wanted mode, especially at oscillation amplitude controlled to be constant. Since this resonance frequency especially is also dependent on the instantaneous density of the medium, commercially available Coriolis mass flow meters can measure, in addition to mass flow, also the density of media flowing in the measuring tube. Furthermore, it is also possible, as shown for example in U.S. Pat. Nos. 6,651,513 or 7,080,564, using measuring transducers of vibration type, to directly measure viscosity of the medium flowing through the measuring tube, for example based on an exciter power required for exciting the oscillations.
In the case of measuring transducers with two measuring tubes, these are normally linked into the process line via a distributor piece on the inlet side, extending between the measuring tubes and a connecting flange on the inlet side, as well as via a distributor piece on the outlet side, extending between the measuring tubes and a connecting flange on the outlet side. In the case of measuring transducers having a single measuring tube, such normally communicates with the process line via an essentially straight piece of connecting tube which opens into the inlet side of the measuring tube, as well as an essentially straight piece of connecting tube which opens into the outlet side of the measuring tube. Furthermore, each of the illustrated measuring transducers having a single measuring tube includes, composed of a single piece or multiple parts, at least one tubular, box-shaped, or plate-shaped counteroscillator, which, with formation of a first coupling zone, is coupled to the inlet side of the measuring tube, and, with formation of a second coupling zone, is coupled to the outlet side of the measuring tube, and which in operation essentially rests, or oscillates equally and oppositely to the measuring tube, that is, with the same frequency and opposite phase. The inner part of the measuring transducer, formed by measuring tube and counteroscillator, is normally held in a protective, measuring transducer housing alone by means of the two pieces of connecting tube, via which the measuring tube communicates with the process line during operation, especially in a way enabling oscillation of the inner part relative to the measuring tube. In the case of measuring transducers shown in, for example, U.S. Pat. Nos. 5,291,792, 5,796,010, 5,945,609, 7,077,014, US-A 2007/0119264, WO-A 01 02 816, or also WO-A 99 40 394, having a single, essentially straight, measuring tube, the latter and the counteroscillator are oriented essentially coaxially to one another, as is common in conventional measuring transducers. In standard measuring transducers of the previously named type, the counteroscillator normally is also essentially tubular, and is formed as an essentially straight hollow cylinder, which is arranged in the measuring transducer such that the measuring tube is at least partially surrounded by the counteroscillator. Used as materials for such counteroscillators are normally relatively cost-efficient types of steel, such as structural steel, or free-machining steel, especially when titanium, tantalum, or zirconium are used for the measuring tube.
The exciter mechanism of measuring transducers of the type being discussed normally has at least one, usually electrodynamic, magnet assembly, serving as oscillation exciter, and acting differentially on the at least one measuring tube, and the, in given cases, present, counteroscillator, or the, in given cases, present, other measuring tube, while the sensor arrangement includes an inlet-side oscillation sensor, most often also electrodynamic, as well as, on the outlet side, an oscillation sensor of essentially the same construction. Usually, at least the magnet assemblies are essentially of the same construction. Such magnet assemblies serving as oscillation transducers of standard measuring transducers of vibration type are formed by means of a magnetic coil (in the case of measuring transducers with one measuring tube and a counteroscillator coupled thereto, the coil is normally mounted on the latter), as well as by means of an elongated, especially rod-shaped, permanent magnet, which, serving as an armature, interacts with the at least one magnetic coil, especially plunging into the coil, and which is mounted correspondingly to the measuring tube to be vibrated. This has the advantage, for example, that, by means of the magnet assemblies, the oscillatory movements between the vibrating measuring tube and its counterpart, that is, the, in given cases, present counteroscillator or the, in given cases, present, other measuring tube, can be differentially registered, or produced, as the case may be. The permanent magnet and the magnetic coil serving as exciter, or sensor, coil are, in such case, normally oriented essentially coaxially to one another. Additionally, in the case of conventional measuring transducers, the magnet assembly serving as oscillation exciter is normally formed and positioned in the measuring transducer in such a way that it acts essentially centrally on the at least one measuring tube. In such case, the magnet assembly serving as oscillation exciter is, as shown, for example, also in the measuring transducers disclosed in U.S. Pat. Nos. 5,796,010, 6,840,109, 7,077,014 or 7,017,424, usually mounted at least pointwise along an imaginary central peripheral line of the measuring tube on its outer side. Alternatively to oscillation exciters formed by means of a magnet assembly acting centrally and directly to the measuring tube, exciter mechanisms formed, as provided in U.S. Pat. Nos. 6,557,422, 6,092,429 or 4,823,614 among others, for example, by means of two magnet assemblies mounted not in the center of the measuring tube, but, instead, shifted, respectively, toward its inlet and outlet sides, can also be used, or, as provided in U.S. Pat. Nos. 6,223,605 or 5,531,126, among others, exciter mechanisms formed, for example, by means of a magnet assembly working between the, in given cases, present counteroscillator and the measuring transducer housing, are also used.
In the case of most market-ordinary measuring transducers of vibration-type, the oscillation sensors of the sensor arrangement are, such as already indicated, at least to the extent that they work according to the same principle of action, embodied with essentially equal construction to that of the at least one oscillation exciter. Accordingly, also the oscillation sensors of such a sensor arrangement are most often, in each case, formed by means of at least one coil, which is usually affixed to the, in given cases, present counteroscillator and through which, at least at times, a variable magnetic field passes, and, associated therewith, at least at times, supplied with an induced measurement voltage, as well as a magnetic armature, which is permanently affixed to the measuring tube and delivers the magnetic field interacting with the at least one coil. Each of the aforementioned coils is, moreover, connected with the mentioned operating, and evaluating, electronics of the in-line measuring devices by means of at least one pair of electrical connecting lines, which most often are led on an as short as possible paths from the coils via the counteroscillator to the transducer housing.
As, among other things, discussed in the initially mentioned US-A 2008/0141789, U.S. Pat. Nos. 6,920,798, 5,731,527, 7,318,356, 6,868,740, 6,758,102, 5,301,557, 5,576,500, or 5,734,112, measuring transducers of vibration-type and, insofar, the entire therewith formed measuring system can have, besides the initially mentioned sensitivity to the primary measured variables, mass flow rate or density and, in given cases, also viscosity, also a certain cross sensitivity to pressure, this, especially, also in the case, in which the medium has two, or more, phases, for instance, in the case of a mixture of liquid and gas. This pressure sensitivity can lead, at times, to a, when also slight, but, because of the desired high accuracy of measurement, nevertheless not directly disregardable corruption of the primary measured value, such as, for instance, the mass flow, and compensating measures corresponding to the measuring errors can be required.
An opportunity for counteracting the pressure sensitivity of measuring systems of the type being discussed can, such as provided e.g. in U.S. Pat. Nos. 6,920,798, 5,731,527 or 5,301,557, be to reduce the cross sensitivity of the measuring transducer with mechanical means, such as, for instance, metal rings encircling the measuring tube coaxially or ceramic windings or through application of comparatively thick walled, measuring tubes. Conversely, such as, for example, also provided in US-A 2008/0034893, the pressure sensitivity of the measuring transducer can, in advantageous manner, however, also be utilized to register the pressure intentionally as another measured variable of the measuring system formed by means of the measuring transducer, and, based thereon, to perform a measurement error compensation. Alternatively thereto or in supplementation thereof, the pressure supplementally ascertained by means of the measuring transducer can also be output in the form of validated measured values of the measuring system, used for a measuring system internal, self-diagnosis of the measuring system and/or applied for monitoring predetermined qualities of the medium. The ascertaining the pressure can be implemented, in the case of conventional Coriolis, mass flow measuring devices, for example, by means of strain gages, which, such as provided in US-A 2008/0141789 or U.S. Pat. No. 6,868,740, are placed on the at least one measuring tube or on one of the mentioned connecting tube pieces, and/or, such as, for example, shown in U.S. Pat. Nos. 7,318,356, 5,576,500 or 5,734,112, by means of multimodal exciting of the measuring tube as well as by physical mathematical models furnished in the evaluating circuit.
A disadvantage of the solutions known from the state of the art for pressure measurement by means of measuring transducers of vibration-type is, however, to be seen in the fact that they are not always exact enough for a highly precise, largely pressure independent, or pressure compensated, measuring of the mass flow, e.g. the mass flow rate, or that, supplementally to the unavoidable, corresponding modifying of the evaluating circuit, yet additional sensors, of different kind in comparison to the primary oscillation sensors, such as, for instance, strain gages, must be used and must be affixed directly on measuring tube segments assuming the temperature of the medium and, in given cases, vibrating, or that correspondingly modified exciter mechanisms and/or correspondingly modified driver electronics must be used. Associated therewith, both experimental effort for calibrating such measuring systems as well as also an increased test effort for the purpose of assuring the durability of the additional sensors and/or electronic components can be expected.
An object of the invention is, consequently, to improve measuring systems formed by means of measuring transducers of vibration-type toward the goal of enabling therewith a highly accurate measuring of the mass flow, e.g. the mass flow rate, also in the case of pressure of the through flowing medium fluctuating over a broad range, in given cases, also a sufficiently precise measuring of the pressure itself in the sense of producing validated, measured values, especially, also combined with application of measurements technology proven in such measuring systems, such as, for instance, established oscillation sensors or also technologies and architectures of established evaluating circuits.
For achieving the object, the invention resides in a measuring system for flowable, especially fluid, media, especially a measuring system developed as a compact measuring device and/or a Coriolis, mass flow, measuring device, which measuring system includes a measuring transducer through which a medium flows during operation, at least at times, and which generated primary signals influenced by at least one measured variable characterizing the flowing medium, especially a mass flow, a density, a pressure, a viscosity etc.; as well as an evaluating circuit electrically coupled with the measuring transducer and processing the primary signals delivered by the measuring transducer to measured values. The measuring transducer of the measuring system of the invention includes: At least one measuring tube, for example, a measuring tube at least sectionally curved, vibrating during operation, at least at times, and serving for conveying medium to be measured; an exciter mechanism having at least one oscillation exciter, for example, an electrodynamic, oscillation exciter, acting on the measuring tube for causing the at least one measuring tube to vibrate; as well as a sensor arrangement serving for registering oscillations of the measuring tube and having a first oscillation sensor, for example, an electrodynamic, first oscillation sensor, arranged on the measuring tube, for example, on the inlet side and/or on a side of the measuring tube occupied by the oscillation exciter, and spaced from the at least one oscillation exciter, for delivering a first primary signal of the measuring transducer representing vibrations of the measuring tube; and a second oscillation sensor, for example, an electrodynamic, second oscillation sensor, arranged to the measuring tube, for example, on the outlet side and/or on a side of the measuring tube occupied by the first oscillation sensor, and spaced from the first oscillation sensor, for example, also spaced equally far from the at least one oscillation exciter as the first oscillation sensor, for delivering a second primary signal of the measuring transducer, for example, simultaneously with the first primary signal, representing vibrations of the measuring tube; as well as a third oscillation sensor, for example, an electrodynamic, third oscillation sensor, arranged to the measuring tube, for example, on a side of the measuring tube occupied by the first oscillation sensor, and spaced both from the first oscillation sensor as well as also from the second oscillation sensor, for example, also from the at least one oscillation exciter, for delivering a third primary signal of the measuring transducer, for example, simultaneously with the first primary signal and/or simultaneously with the second primary signal, representing vibrations of the measuring tube. Additionally, the evaluating circuit of the measuring system of the invention generated, at least at times, both by means of the first primary signal as well as also by means of the second primary signal as well as by means of the third primary signal, for example, based on a phase difference existing between the first primary signal and the second primary signal and/or based on a phase difference existing between the third primary signal and another of the primary signals, a measured value of mass flow, for example, a digital, measured value of mass flow, which represents, instantaneously, a mass flow rate, m, of medium flowing through the measuring transducer. Alternatively or in supplementation, it is additionally provided, that the evaluating circuit, at least at times, both by means of the first primary signal as well as also by means of the second primary signal as well as by means of the third primary signal, for example, based on a phase difference existing between the first primary signal and the second primary signal and/or based on a phase difference existing between the first primary signal and the third primary signal, generated a pressure measured value, for example, a digital, pressure measured value, which represents, instantaneously, a pressure, p, in medium flowing through the measuring transducer, for example, a static pressure reigning in the at least one measuring tube.
According to a first embodiment of the invention, it is additionally provided, that the third oscillation sensor is placed on a measuring tube segment of the measuring tube extending between the first oscillation sensor and the at least one oscillation exciter.
According to a second embodiment of the invention, it is additionally provided, that the evaluating circuit recurringly during operation produces a phase difference value of first type, which represents, instantaneously, the phase difference, ΔφI, existing between the first primary signal and the second primary signal.
According to a third embodiment of the invention, it is additionally provided, that the evaluating circuit recurringly during operation produces a phase difference value of second type, which represents, instantaneously, the phase difference, ΔφII, existing between the third primary signal and another of the primary signals.
According to a fourth embodiment of the invention, it is additionally provided, that the evaluating circuit, by means of the first primary signal as well as at least one other of the primary signals of the measuring transducer, for example, the second primary signal, produces an interimly representing and/or not sufficiently exactly representing and/or digital, provisional measured value of mass flow of first type, for example, a provisional mass flow, m, of medium flowing through the measuring transducer, for example, based on a phase difference, ΔφI, existing between the first primary signal and the second primary signal. Developing this embodiment of the invention, further, it is additionally provided, that the evaluating circuit generates the provisional measured value of mass flow of first type based on the phase difference, ΔφI, of first type existing between the first primary signal and the second primary signal as well as with application of a measuring system parameter, for example, an experimentally earlier ascertained and/or internally stored, measuring system parameter, representing a first zero point, ZEROI, of the measuring system, and with application of a, for example, experimentally earlier ascertained and/or internally stored, measuring system parameter representing a first sensitivity, SPANI, of the measuring system. The measuring system parameter representing the first zero point, ZEROI, of the measuring system can correspond especially to a phase difference, ΔφI0, measured between the first primary signal and the second primary signal, in the case of medium standing in the measuring tube, i.e. mDESIRED=0, and/or to an provisional measured value of mass flow of first type ascertained in the case of medium standing in the measuring tube, i.e. mDESIRED=0. The measuring system parameter representing the first sensitivity, SPANI, of the measuring system can, in turn, correspond to a phase difference, ΔφI1, measured between the first primary signal and the second primary signal in the case of supplying the measuring transducer with a flowing medium of known and/or impressed, mass flow rate, mDESIRED< >0, and/or a rate ascertained by means of a reference, mass flow measuring device and/or to a phase difference value of first type ascertained in the case of supplying the measuring transducer with a flowing medium of known and/or impressed, mass flow rate, mDESIRED< >0, and/or also to a phase difference, ΔφI1, in the case of supplying the measuring transducer with a flowing medium also of known, average static pressure, pDESIRED1>0, measured between the first primary signal and the second primary signal, for example, an impressed, average static pressure and/or an average static pressure ascertained by means of a reference, pressure measuring device.
According to a fifth embodiment of the invention, it is additionally provided, that the evaluating circuit produces, by means of the third primary signal as well as at least one other of the primary signals of the measuring transducer, for example, the first primary signal and/or the second primary signal, a provisional measured value of mass flow of second type, for example, one interimly and/or not sufficiently exactly representing a mass flow, m, of medium flowing through the measuring transducer, and/or a digital one, for example, one based on a phase difference, ΔφII, existing between the third primary signal and another of the primary signals. Developing this embodiment of the invention, further, it is additionally provided, that the evaluating circuit generates the provisional measured value of mass flow of second type based on a phase difference, ΔφII, of second type existing between the third primary signal and another of the primary signals as well as with application of a measuring system parameter, for example, an experimentally earlier ascertained and/or internally stored, measuring system parameter, representing a second zero point, ZEROII, of the measuring system and with application of a measuring system parameter, for example, an experimentally earlier ascertained and/or internally stored, measuring system parameter, representing a second sensitivity, SPANII, of the measuring system. The measuring system parameter representing the second zero point, ZEROII, of the measuring system can correspond especially to a phase difference, ΔφII0, measured between the third primary signal and another of the primary signals in the case of medium standing in the measuring tube, i.e. mDESIRED=0, and/or correspond to a provisional measured value of mass flow of second type ascertained in the case of medium standing in the measuring tube, i.e. mDESIRED=0. The measuring system parameter representing the second sensitivity, SPANII, of the measuring system can, in turn, correspond to a phase difference, ΔφII1, between the third primary signal and another of the primary signals, measured in the case of supplying the measuring transducer with a flowing medium of known mass flow rate, mDESIRED< >0, for example, an impressed one and/or one ascertained by means of a reference, mass flow measuring device, and/or to a phase difference value of second type ascertained in the case of supplying the measuring transducer with a flowing medium of known mass flow rate, mDESIRED< >0, for example, an impressed one and/or one ascertained by means of a reference, mass flow measuring device, and/or also to a phase difference, ΔφII1, between the third primary signal and another of the primary signals, measured in the case of supplying the measuring transducer with a flowing medium also of known, average static pressure, pDESIRED1>0, for example, an impressed one and/or one ascertained by means of a reference, pressure measuring device.
According to a sixth embodiment of the invention, it is additionally provided, that the evaluating circuit generates the measured value of mass flow with application of a measuring system parameter, for example, an experimentally earlier ascertained and/or internally stored, measuring system parameter, representing a relative pressure dependence, PRESSUREI, of the first sensitivity, SPANI, of the measuring system referenced, for example, to the first sensitivity, SPANI, of the measuring system and/or that the evaluating circuit generates the measured value of mass flow with application of a measuring system parameter, for example, an experimentally earlier ascertained and/or internally stored, measuring system parameter, representing a relative pressure dependence, PRESSUREII, of the second sensitivity, SPANII, of the measuring system referenced, for example, to the second sensitivity, SPANII, of the measuring system.
The measuring system parameter representing the pressure dependence, PRESSUREI, of the first sensitivity, SPANI, of the measuring system can be ascertained based on a phase difference, ΔφIp1, measured between the first primary signal and the second primary signal in the case of supplying the measuring transducer with a flowing medium of known first average static pressure, pDESIRED1, for example, an impressed one and/or one ascertained by means of a reference, pressure measuring device, and based on a phase difference, ΔφIp2, measured between the first primary signal and the second primary signal in the case of supplying the measuring transducer with a flowing medium of known, second average static pressure, pDESIRED2, for example, an impressed one and/or one ascertained by means of a reference, pressure measuring device, for example, also with application of the evaluating circuit. Additionally, the measuring system parameter representing the pressure dependence, PRESSUREI, of the first sensitivity, SPANI, of the measuring system can be ascertained based on a provisional measured value of mass flow of first type generated in the case of supplying the measuring transducer with a flowing medium of known and/or impressed, first average static pressure, pDESIRED1, and/or by means of a first average static pressure, pDESIRED1, ascertained by a reference, pressure measuring device, and based on a provisional measured value of mass flow of first type generated in the case of supplying the measuring transducer with a flowing medium of known and/or impressed, second average static pressure, pDESIRED2, and/or a second average static pressure, pDESIRED2, ascertained by means of a reference, pressure measuring device, for example, also with application of the evaluating circuit.
The measuring system parameter representing the pressure dependence, PRESSUREII, of the second sensitivity, SPANII, of the measuring system can, in turn, be ascertained based on a phase difference, ΔφIIp1, measured between the third primary signal and another of the primary signals in the case of supplying the measuring transducer with a flowing medium of known, first average static pressure, pDESIRED1, for example, an impressed one and/or one ascertained by means of a reference, pressure measuring device and based on a phase difference, ΔφIIp2, measured between the third primary signal and another of the primary signals in the case of supplying the measuring transducer with a flowing medium of known, second average static pressure, pDESIRED2, for example, an impressed one and/or one ascertained by means of a reference, pressure measuring device, for example, also with application of the evaluating circuit. Additionally, the measuring system parameter representing the pressure dependence, PRESSUREII, of the second sensitivity, SPANII, of the measuring system can also be ascertained based on a provisional measured value of mass flow of second type generated in the case of supplying the measuring transducer with a flowing medium of known, first average static pressure, pDESIRED1, for example, an impressed one and/or one ascertained by means of a reference, pressure measuring device, and based on a provisional measured value of mass flow of second type generated in the case of supplying the measuring transducer with a flowing medium of known, second average static pressure, pDESIRED2, for example, an impressed one and/or one ascertained by means of a reference, pressure measuring device, for example, also with application of the evaluating circuit.
According to a seventh embodiment of the invention, it is additionally provided, that the evaluating circuit produces during operation, recurringly, a phase difference value of first type, which represents, instantaneously, the phase difference, ΔφI, existing between the first primary signal and the second primary signal, as well as a phase difference value of second type, which represents, instantaneously, the phase difference, ΔφII, existing between the third primary signal and another of the primary signals type, and that the evaluating circuit generates the measured value of mass flow and/or the measured value of pressure by means of the phase difference value of first type and by means of the phase difference value of second type.
According to an eighth embodiment of the invention, it is additionally provided, that the evaluating circuit produces, by means of the first primary signal as well as at least one other of the primary signals of the measuring transducer, for example, the second primary signal, a interimly and/or not sufficiently exactly representing of an instantaneous mass flow rate, m, of medium flowing through the measuring transducer and/or a digital, provisional measured value of mass flow of first type, for example, based on a phase difference, ΔφI, existing between the first primary signal and the second primary signal, and that the evaluating circuit produces, by means of the third primary signal as well as at least one other of the primary signals of the measuring transducer, for example, the first primary signal and/or the second primary signal, a provisional measured value of mass flow of second type interimly and/or not sufficiently exactly representing of an instantaneous mass flow rate, m, of medium flowing through the measuring transducer and/or a digital, provisional measured value of mass flow of second type, for example, a provisional measured value of mass flow of second type based on a phase difference, ΔφII, existing between the third primary signal and another of the primary signals. Developing this embodiment of the invention further, it is additionally provided, that the evaluating circuit generates the measured value of mass flow and/or the measured value of pressure, in each case, by means of the provisional measured value of mass flow of first type and by means of the provisional measured value of mass flow of second type.
According to a ninth embodiment of the invention, it is additionally provided, that the first oscillation sensor and the third oscillation sensor are so placed in the measuring transducer, that an amplitude of the first primary signal is influenced in smaller measure by an average static pressure reigning instantaneously in the at least one measuring tube than is an amplitude of the third primary signal.
According to a tenth embodiment of the invention, it is additionally provided, that the second oscillation sensor and the third oscillation sensor are so placed in the measuring transducer, that an amplitude of the second primary signal is influenced in smaller measure by an average static pressure reigning instantaneously in the at least one measuring tube than is an amplitude of the third primary signal.
According to an eleventh embodiment of the invention, it is additionally provided, that the first oscillation sensor and the second oscillation sensor are so placed in the measuring transducer, that an amplitude of the first primary signal and an amplitude of the second primary signal are influenced in equal measure by an average static pressure reigning instantaneously in the at least one measuring tube.
According to a twelfth embodiment of the invention, it is additionally provided, that the at least one measuring tube is embodied at least sectionally essentially with V shape.
According to a thirteenth embodiment of the invention, it is additionally provided, that the at least one measuring tube is embodied at least sectionally essentially U shape.
According to a fourteenth embodiment of the invention, it is additionally provided, that at least the first oscillation sensor and the second oscillation sensor are of equal construction relative to one another.
According to a fifteenth embodiment of the invention, it is additionally provided, that at least the first oscillation sensor and the third oscillation sensor are of equal construction relative to one another.
According to a sixteenth embodiment of the invention, it is additionally provided, that the first oscillation sensor is arranged on the inlet side and the second oscillation sensor on the outlet side of the at least one measuring tube.
According to a seventeenth embodiment of the invention, it is additionally provided, that the at least one measuring tube has a measuring tube segment, for example, an at least sectionally curved, measuring tube segment, extending essentially freely oscillating, between an end of the measuring tube defining an inlet-side, oscillation node of oscillations of the measuring tube and an end of the measuring tube defining an outlet-side, oscillation node of oscillations. Additionally, it is, in such case, provided, that both the first oscillation sensor, as well as also the second oscillation sensor, as well as also the third oscillation sensor are so placed in the measuring transducer, that each of the three oscillation sensors registers, for example, predominantly or exclusively, vibrations of the essentially freely oscillating measuring tube segment and/or that the at least one measuring tube is excited during operation by means of the exciter mechanism, at least at times, in a wanted mode, in which it executes, for example, predominantly or exclusively, bending oscillations about an imaginary, oscillation axis, for example, one parallel to or coincident with a longitudinal axis of the measuring transducer, imaginarily connecting ends of the at least one measuring tube, for example, with a single and/or with a lowest resonance frequency, and/or that each of the at least three primary signals of the measuring transducer, for example, primary signals generated simultaneously, has, in each case, a signal component, for example, a dominating signal component and/or a signal component corresponding to the wanted mode, with a signal frequency corresponding to the bending oscillations in the wanted mode and/or to a resonance frequency, for example, a lowest resonance frequency, of the at least one measuring tube.
According to an eighteenth embodiment of the invention, it is additionally provided, that the evaluating circuit generates, at least at times, by means of at least one of the primary signals, a density measured value, for example, a digital, density measured value, which represents, instantaneously, a density, ρ, of medium flowing through the measuring transducer.
According to a nineteenth embodiment of the invention, it is additionally provided, that the evaluating circuit generates, at least at times, by means of at least one of the primary signals, a viscosity measured value, for example, a digital, viscosity measured value, which represents a viscosity, η, of medium flowing through the measuring transducer.
According to a first further development of the invention, the measuring system further includes a driver circuit, for example, a driver circuit communicating during operation with the evaluating circuit, electrically coupled with the measuring transducer, and delivering at least one exciter signal controlling its exciter mechanism.
According to a second further development of the invention, the measuring transducer further includes a counteroscillator, for example, a counteroscillator oscillating during operation essentially with opposite phase to that of the measuring tube and/or a counteroscillator parallel to the measuring tube, affixed to the measuring tube to form a first coupling zone on the inlet side of the measuring tube and to form a second coupling zone on the outlet side of the measuring tube. Additionally, it is, in such case, provided, that both the first oscillation sensor, as well as also the second oscillation sensor, as well as also the third oscillation sensor are so placed in the measuring transducer, that each of the three oscillation sensors, for example, predominantly or exclusively, registers, for example, differentially, oscillations of the at least one measuring tube relative to the counteroscillator; and/or that measuring tube and counteroscillator oscillate with opposite phase relative to one another, during operation, at least at one, shared, oscillation frequency; and/or that both the first primary signal as well as also the second primary signal as well as also the third primary signal represent, for example, opposite-equal, oscillatory movements of the at least one measuring tube relative to the counteroscillator; and/or that the oscillation sensors, for example, equally-constructed, oscillation sensors, register, for example, simultaneously and/or differentially, vibrations of the at least one measuring tube, for example, a U shaped or V shaped, measuring tube, and the counteroscillator, for example, a U shaped or V shaped counteroscillator.
According to a third further development of the invention, the sensor arrangement further includes, for example, an electrodynamic, fourth oscillation sensor arranged on the measuring tube and spaced both from the first oscillation sensor as well as also from the second oscillation sensor as well as also from the third oscillation sensor, for example, also equally far as the third oscillation sensor is from the at least one oscillation exciter, for example, arranged on a side of the measuring tube occupied by the first oscillation sensor and/or by the second oscillation sensor and/or by the third oscillation sensor, which delivers, especially simultaneously with the first and second primary signals and/or simultaneously with the third primary signal, a fourth primary signal of the measuring transducer representing vibrations of the measuring tube.
According to a first embodiment of the third further development, it is, in the case of the measuring system of the invention, additionally provided, that the evaluating circuit generates the measured value of mass flow also by means of the fourth primary signal.
According to a first embodiment of the third further development, it is, in the case of the measuring system of the invention, additionally provided, that at least the third oscillation sensor and the fourth oscillation sensor are of equal construction relative to one another.
According to a first embodiment of the third further development, it is, in the case of the measuring system of the invention, additionally provided, that the third oscillation sensor is arranged on the inlet side and the fourth oscillation sensor on the outlet side of the at least one measuring tube.
According to a first embodiment of the third further development, it is, in the case of the measuring system of the invention, additionally provided, that the third oscillation sensor and the fourth oscillation sensor are so placed in the measuring transducer, that an amplitude of the third primary signal and an amplitude of the fourth primary signal are influenced in equal measure by an internal pressure reigning in the at least one measuring tube.
According to a first embodiment of the third further development, it is, in the case of the measuring system of the invention, additionally provided, that the fourth oscillation sensor is placed on a measuring tube segment of the measuring tube extending between the second oscillation sensor and the at least one oscillation exciter.
According to a first embodiment of the third further development, it is, in the case of the measuring system of the invention, additionally provided, that the evaluating circuit recurringly during operation produces a phase difference value of second type, which represents, instantaneously, the phase difference, ΔφII, type existing between the third primary signal and another of the primary signals, and that the phase difference value of second type represents the phase difference, ΔφII, existing between the third primary signal and the fourth primary signal (s4).
According to a first embodiment of the third further development, it is, in the case of the measuring system of the invention, additionally provided, that the evaluating circuit, by means of the third primary signal as well as at least one other of the primary signals of the measuring transducer, for example, the first primary signal and/or the second primary signal, produces, for example, based on a phase difference, ΔφII, existing between the third primary signal and another of the primary signals, a provisional measured value of mass flow of second type, for example, one interimly and/or not sufficiently exactly representing a mass flow, m, of medium flowing through the measuring transducer and/or a digital one, and that the evaluating circuit generates the provisional measured value of mass flow of second type both by means of the third primary signal as well as also by means of the fourth primary signal, for example, based on a phase difference, ΔφII, existing between the third primary signal and the fourth primary signal.
A basic idea of the invention is to register the different influences of pressure reigning in the flowing medium for the individual, mutually spaced, oscillation sensors, and, associated therewith, the cross sensitivities of the sensor arrangement, or the measuring transducer, on pressure during operation as a function of the location of installation the respective oscillation sensors and, among other things, in a manner compensating the influence of pressure on the measured mass flow. Alternatively thereto or in supplementation thereof, the site dependence of the cross sensitivity of the sensor arrangement, or the measuring transducer, on pressure can also be used to register the pressure, as such, by means of measuring transducers of vibration-type, or the therewith produced, primary signals representing measuring tube oscillations.